Need Help Understanding Anemia Morophological Categories

EricJRN, MSN, RN · Apr 16, 2006

You're right about the lack of Hb being the cause of small RBC's in microcytic anemias.

Macrocytic anemias are usually caused by B12 or folate deficiencies and they are associated with impaired DNA synthesis. When you have impaired synthesis of DNA, you will have some 'skipped' cell divisions. Because of the skips, you'll have cells coming out at a slower pace, so they're larger.

Daytonite, BSN, RN · Apr 16, 2006

morphologic classification of anemias is the most common and refers to the cell size and hemoglobin content. fyi. . .the suffix "cytic" refers to cell size. the suffix "chromic" refers to hemoglobin content.

macrocytic anemias

let me see if i can give you an explanation about why the rbc's are enlarged in macrocytic anemia that you can understand. this can be very complex stuff, so hang in there as i take a crack at this for you. bone marrow. all rbc's start there. each rbc comes from a stem cell in the bone marrow. somewhere i'm sure you've got the term erythropoiesis written down. erythropoiesis is the medical terminology for the formation of red blood cells. both vitamin b12 and folate are necessary in the process of erythropoiesis. a deficiency of either or both causes all hell to break lose with dna and rna synthesis of red blood cells and funky things start to happen when the process of erythropoiesis tries to get underway in the stem cells of the bone marrow. right off the bat the stem cells start cranking out abnormally enlarged megaloblasts, the medical term for an enlarged germ or "baby" red blood cell. this is a direct result of their defective dna that is causing errors in its replication. you need to understand that in the normally developing rbc the dna is responsible for creating and building up the cytoplasm and it's structures while the rna is the project manager and leader for what is going on in the nucleus, and that is primarily the synthesis of hemoglobin. think of the dna and rna of one of these megaloblastic (defective) cells as being tweedle dum and tweedle dee trying to get a complex job completed. they are both screwing up the process. here is what is going on. the fat old slow moving dna is proceeding at a snails pace. space cadet rna is doing his thing at a fairly normal pace, but not paying attention to what is going on with dna. when they meet up is when they know they have finished the job. in a more professional tone, the cytoplasm (dna controlled) lags in development while the synthesis of hemoglobin in the nucleus by the rna continues because it has no ability to shut itself off. it has to wait for the cytoplasm to "catch up" in its growth and then it can shut down its production of hemoglobin. so busy little space cadet rna is mindlessly busting it's hump and cranking out loads of hemoglobin while it waits for the fat old slow moving dna controlled cytoplasmic growth to catch up. when the two finally meet up you have an enlarged cell that has an extraordinarily larger load of hemoglobin. viola! this is your macrocytic rbc.

microcytic anemias

iron is an essential component of hemoglobin. erythropoiesis starts in the bone marrow normally, but due to the lack of iron the mature rbcs just don't have sufficient amounts of hemoglobin in them to do the job they were intended to do. you can't build a complete house if you don't have enough wood. it's that simple. the abnormally small amount of hemoglobin in these cells contributes to their microcytic size.

a second reason for microcytic anemia is due to errors in hemoglobin formation. the process is quite complex and involves deficiencies in building components or decreased activity of enzymes that catalyze the chemical synthesis of hemoglobin within the mitochondria. the cause may be the genetic or acquired (due to drugs or toxins) dysfunction of iron metabolism in the erythroblasts. the dysfunctional hemoglobin that is produced lacks iron and often porphyrin (the purple pigment in hemoglobin) as well. these are the sideroblastic anemias. suffice it to say that the hemoglobin in these cells is a screwed up mess where only half the effort got put into the work and some of the parts were left out.

hope that helps. sorry for the humor. i've put together some links from family practice notebook on the anemias. don't know if you really need that stuff, but perhaps others reading this will. there's lots of other links to other anemias at those web pages.

http://www.fpnotebook.com/hem4.htm - macrocytic anemias. diagnosis, pathophysiology, causes, and classifications

http://www.fpnotebook.com/hem7.htm - microcytic anemias. causes, labs.

http://www.fpnotebook.com/hem3.htm - how anemias are differentiated and evaluated

http://www.fpnotebook.com/hem2.htm - the clinical signs, symptoms and history that a patient with anemia presents.

happy easter!

Lisa CCU RN, RN · Apr 17, 2006

Ok, first, Daytonite, why haven't you been made a moderator? Second, where do you get all this great information from? Third, can you please come teach my patho class?

Actually, the semester is almost over for me, so it'd do me little good, but you would do a HUGE service to future nursing students if you taught in the classroom OR clinicals. You have such great information and websites!

Great Job!

Daytonite, BSN, RN · Apr 17, 2006

Ok, first, Daytonite, why haven't you been made a moderator? Second, where do you get all this great information from? Third, can you please come teach my patho class?
Actually, the semester is almost over for me, so it'd do me little good, but you would do a HUGE service to future nursing students if you taught in the classroom OR clinicals. You have such great information and websites!
Great Job!

Thank you. I have been asked to be a moderator. I declined. I have a little reference library sitting in front of me at my computer. Some of the books are for nursing, some for leadership and management, some for medical coding, some for medical procedures, some math books (I love math). The information for the anemia came from one of my pathophysiology books--I really did not know the answer myself. I had to read the material in 2 paragraphs several times. I figured that if I was having that difficult a time trying to get it to click in my mind, what must the OP be going through. One thing going for me is that I am not pressed by the deadline of having to know it for a test or having to carry the burden of studying for 4 other classes. I've been a closet teacher for years. Teaching is what I originally wanted to do coming out of high school. My life, however, took a different direction. I haven't ever regretted going into nursing. I believe learning should be fun and the complex should be made as simple as possible. However, with the way I can ramble on and on when I'm writing it makes you wonder.

cardiacRN2006, ADN, RN · Apr 17, 2006

Have you considered becoming a clinical instructor? You'd be great at that!

Daytonite, BSN, RN · Apr 17, 2006

Have you considered becoming a clinical instructor? You'd be great at that!

Thanks. I wish I could. I have a back problem and cannot tolerate to stand longer than several minutes. I would not be able to navigate around a facility well enough.

Lisa CCU RN, RN · Apr 17, 2006

Thanks. I wish I could. I have a back problem and cannot tolerate to stand longer than several minutes. I would not be able to navigate around a facility well enough.

That is too bad, you'd be great at it, it seems.